[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130552
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 13 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

HUMBERTO HAS BEEN UPGRADED TO A HURRICANE. AT 13/0515 UTC...THE
CENTER OF HURRICANE HUMBERTO WAS LOCATED NEAR 29.4N 94.4W OR
ABOUT 17 NM EAST OF GALVESTON TEXAS...AND ABOUT 13 NM SOUTH OF
HIGH ISLAND TEXAS MOVING NNE AT 7 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH
GUSTS TO 85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
DOPPLER RADAR DATA HAS DISPLAYED AN IMPROVED STRUCTURE WITH AN
EYE-LIKE FEATURE AND WELL DEFINED BANDING N OF THE CENTER
EVIDENT. BASED ON THIS DATA...SOME OF THE HEAVIEST RAINS AND
STRONGEST WINDS WILL BEGIN TO IMPACT THE COASTLINE SHORTLY.
TOTAL RAINFALL AMOUNTS OF 5 TO 10 INCHES ARE EXPECTED ALONG THE
TRACK OF HUMBERTO THROUGH EASTERN TEXAS AS WELL AS WESTERN AND
CENTRAL LOUISIANA...WITH ISOLATED MAXIMUM ACCUMULATIONS OF 15
INCHES POSSIBLE.

TROPICAL DEPRESSION EIGHT IS CENTERED NEAR 13.4N 46.4W AT
13/0300  UTC OR ABOUT 875 NM EAST OF THE LESSER ANTILLES MOVING
WEST NEAR 10 KT.  ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006
MB.  MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.  THIS DEPRESSION HAS
GENERALLY CHANGED LITTLE THROUGHOUT THE EVENING HOURS WITH THE
LOW-LEVEL CENTER LOCATED TO THE E OF A PERSISTENT AREA OF
MODERATE CONVECTION WHICH EXTENDS ROUGHLY 120 NM W OF THE
CENTER. SOME STRENGTHENING IS EXPECTED IN THE SHORT TERM AS THE
NELY SHEAR IS EXPECTED TO RELAX SLIGHTLY.

...TROPICAL WAVES...

A HIGH AMPLITUDE TROPICAL WAVE IS IN THE E ATLC ALONG 37W S OF
24N MOVING W 15 KT. IN GENERAL...THIS WAVE HAS CHANGED LITTLE
OVER THE PAST COUPLE OF DAYS. THE STRUCTURE REMAINS WELL DEFINED
WITH A LARGE SHIELD OF CYCLONIC TURNING NOTED IN THE LOW TO MID
LEVEL CLOUD FIELD. IN ADDITION...THE UW-CIMSS TPW ANIMATION
REVEALS A LARGE WWD PROPAGATING SURGE OF MOISTENED AIR.  DESPITE
THE FAIR STRUCTURE...DEEP MOISTURE IS SPARSE WITH WIDELY
SCATTERED MODERATE CONVECTION WITHIN 180 NM OF THE AXIS. MORE
ORGANIZED ACTIVITY IS SITUATED AT THE BASE OF THE WAVE WITHIN
THE ITCZ.

TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 77W S OF 23N
MOVING W 15-20 KT.  A SURGE OF MOISTURE ASSOCIATED WITH THIS
FEATURE IS STILL WELL DEFINED ON THE TPW ANIMATION FROM
CIMSS...WHICH WAS THE PRIMARY TOOL USED TO TRACK THIS WAVE AS
LITTLE SIGNATURE IS APPARENT IN CONVENTIONAL SATELLITE IMAGERY.
THE INTERACTION WITH AN UPPER LOW CENTERED JUST S OF CENTRAL
CUBA IS SUPPORTING SCATTERED SHOWERS AND TSTMS OVER CUBA AND A
PORTION OF THE NW CARIB N OF 19N W OF 78W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N18W 11N25W 15N36W 14N45W 9N61W.
SCATTERED MODERATE CONVECTION IS LOCATED FROM 12N-15N E OF 22W
ASSOCIATED WITH THE NEXT TROPICAL WAVE...WHICH WILL LIKELY BE
ADDED TO THE 06Z SYNOPTIC MAP. SIMILAR ACTIVITY IS FROM 6N-8N
BETWEEN 33W-37W AND S OF THE DEPRESSION FROM 11N-13N BETWEEN
40W-45W.

DISCUSSION...

THE GULF OF MEXICO...
NEWLY UPGRADED HURRICANE HUMBERTO IS THE HIGHLIGHT IN THE GULF
OF MEXICO AS IT APPROACHES LANDFALL ON THE GULF COAST. FOR
DETAILS REFER TO THE SPECIAL FEATURE SECTION ABOVE. THE
REMAINDER OF THE REGION REMAINS EMBEDDED IN A MOIST ENVIRONMENT
AS INDICATED BY WATER VAPOR IMAGERY AND THE CIMSS TPW ANIMATION.
THE UPPER FEATURES MAINTAINING THIS WIDESPREAD HIGH LEVEL
MOISTURE PLUME CONSIST OF AN ELONGATED UPPER HIGH OVER THE NW
GULF AND AN UPPER LOW JUST S OF CUBA. IR IMAGERY...BEFORE THE
ECLIPSE...SHOWS ONLY SPOTS OF PRECIP. ONE SOMEWHAT PERSISTENT
AREA...ALSO EVIDENT ON MOSAIC RADAR IMAGERY...IS OVER THE SE
GULF ROUGHLY S OF 27N BETWEEN 83W-85W. WEAKENING POCKETS OF
SCATTERED MODERATE CONVECTION ARE OVER THE W YUCATAN AND ERN BAY
OF CAMPECHE WHERE DIFFLUENCE ALOFT IS MORE PRONOUNCED. ISOLATED
SHOWERS ARE POSSIBLE JUST ABOUT ANYWHERE ELSE IN THE REGION.

THE CARIBBEAN SEA...
A BROAD UPPER LOW HAS BEEN DRIFTING WWD OVER THE PAST 24 HOURS
CENTERED S OF CENTRAL CUBA NEAR 21N79W. DIFFLUENCE ALOFT TO THE
S OF THE UPPER LOW COUPLED WITH THE ITCZ IS ENHANCING CLUSTERS
OF SCATTERED MODERATE CONVECTION OVER THE SW CARIBBEAN AND
PORTIONS OF COSTA RICA...PANAMA AND NICARAGUA ROUGHLY S OF 13N W
OF 80W. THE INTERACTION BETWEEN A WEAK TROPICAL WAVE AND THE
UPPER LOW IS PRODUCING SOME SHOWER ACTIVITY ACROSS THE NW
CARIB...FOR DETAILS SEE ABOVE. THE ERN CARIB IS EXPERIENCING
MOSTLY FAIR WEATHER AS DRIER AIR FROM THE TROPICAL ATLC HAS BEEN
ADVECTED INTO THE AREA AROUND AN UPPER HIGH. MODERATE TO STRONG
TRADE WINDS ARE BLOWING ACROSS THE REGION...STRONGEST BETWEEN
COLOMBIA AND HISPANIOLA WHERE QSCAT DEPICTED A SOLID AREA OF
20-25 KT WINDS.

THE ATLANTIC OCEAN...
TROPICAL DEPRESSION EIGHT IS THE MAIN FEATURE OF INTEREST ACROSS
THE TROPICAL AND SUBTROPICAL ATLC DISCUSSION ZONE. FOR DETAILS
AND REFERENCES REFER TO THE SPECIAL FEATURE SECTION ABOVE.
OTHERWISE...THE ATLC BASIN IS FAIRLY QUIET THIS MORNING. THE SFC
PATTERN HAS GENERALLY CHANGED LITTLE OVER THE PAST COUPLE OF
DAYS. A PAIR OF 1022 MB HIGHS ARE ANALYZED JUST N OF THE REGION
IN THE CENTRAL AND W ATLC NEAR 33N62W AND 37N48W. ANOTHER 1022
MB HIGH IS CENTERED IN THE E ATLC NEAR 33N25W. A SLIGHT WEAKNESS
IN THE SUBTROPICAL RIDGING LIES BETWEEN 35W-45W ASSOCIATED WITH
A TROUGH OF LOW PRES IN THE N CENTRAL ATLC. THIS WEAKNESS HAS
ALLOWED WINDS TO BE FAIRLY LIGHTER IN THAT VICINITY...WITH
MODERATE TRADES OBSERVED ELSEWHERE.

ALOFT...A COMPLEX PATTERN IS IN PLACE ACROSS THE SW ATLC. THE
CONTRIBUTING LARGE SCALE FEATURES CONSIST OF A WESTWARD MOVING
UPPER LOW CENTERED JUST S OF CENTRAL CUBA...THE ERN PERIPHERY OF
THE GULF RIDGE AND ANOTHER UPPER LOW CENTERED NEAR 28N63W. THE
LATTER UPPER LOW ACTUALLY BECAME CUT OFF FROM THE TAIL END OF
THE EXTENSIVE TROUGHING COVERING THE CENTRAL ATLC N OF OF 20N
BETWEEN 32W-54W...ASSOCIATED WITH AFOREMENTIONED TROUGH OF LOW
PRES IN THE N CENTRAL ATLC. THIS PATTERN IS ONLY GENERATING A
SHIELD OF MID TO HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS W OF
70W AND N OF 25N BETWEEN 37W-47W. MUCH OF THE REMAINDER OF THE
AREA IS DOMINATED BY AN E-W RIDGE COVERING THE AREA FROM THE
LESSER ANTILLES EWD WITH A MEAN AXIS ALONG 18N WITH SEVERAL
EMBEDDED ANTICYCLONES. THIS RIDGE AND A CONFLUENT PATTERN...TO
THE S OF A LARGE UPPER LOW NEAR SRN PORTUGAL...IS KEEPING
WEATHER CONDITIONS FAIRLY TRANQUIL.

$$
CANGIALOSI




This weather bulletin was brought to you by:
www.nashvilleweather.net